package basic_practice_1027;

import java.math.BigInteger;
import java.util.Scanner;
/**
 * @author MemoryC
 * */

public class Main {

	public static void main(String[] args) {

		Scanner scanner=new Scanner(System.in);
		
		while(scanner.hasNext()) {

			String ms=scanner.next();
			String ns=scanner.next();
			if(ms.trim().length()==0||ns.trim().length()==0){
				continue;
			}

			if(ms.length()<10&&ns.length()<10&&(ms.length()+ns.length()<10)){
				int m=Integer.parseInt(ms);
				int n=Integer.parseInt(ns);
				float r=m*n;
				if( (m&0x01)==1&&(n&0x01)==1){
					r+=0.41f;
				}
				System.out.printf("%.2f\n",r);
			}else if(ms.length()<19&&ns.length()<19&&(ms.length()+ns.length()<19)){
				long m=Long.parseLong(ms);
				long n=Long.parseLong(ns);
				float r=m*n;
				if( (m&0x01)==1&&(n&0x01)==1){
					r+=0.41f;
				}
				System.out.printf("%.2f\n",r);
			}else{
				BigInteger m=new BigInteger(ms);
				BigInteger n=new BigInteger(ns);
				String r=m.multiply(n).toString();

				if(((m.toString().charAt(m.toString().length()-1))-'0')%2!=0&&((n.toString().charAt(n.toString().length()-1))-'0')%2!=0){
					r+=".41";
				}else{
					r+=".00";
				}
				System.out.println(r);
			}

		}
		scanner.close();
    }
}